The present invention relates to a security system for trailer hitches, and in particular, to a novel trailer ball connected to a security system having two separate alarms selectively set by the driver, one alarm to signal a loose trailer connection, and the other to alert the driver and those in the vicinity of unauthorized unhitching, or theft, of the trailer.
Conventionally, trailer hitches are of the ball and socket type, which allows a secure connection of a socket coupling member of the trailer to the ball of the towing vehicle. The ball and socket arrangement allows a tight connection of the trailer to the towing vehicle, while allowing the trailer to pivot with respect to the ball, thus permitting the vehicle and the trailer to negotiate turns in the road.
However, vibrations, shock, wear and tear, accumulation of dirt, or improper seating of the trailer ball over the socket may cause the hitch assembly to become loose. This loosening may cause an accidental uncoupling of the trailer socket from the ball of the towing vehicle while the vehicle is in motion, with disastrous results, both in personal injury and property loss. As the hitch assembly is never visible to the driver while the vehicle is in motion, a device to monitor the integrity of the trailer hitch connection from within the cab of the vehicle is needed to assure the safety the driver and to safeguard the trailer. Also needed is a security device to monitor the trailer coupling for unauthorized unhitching or theft of the trailer after the vehicle's ignition has been turned off and to sound a loud alarm if such an unauthorized uncoupling or theft is detected.
Various solutions have been proposed to indicate a secure trailer hitch connection and to alert the driver of the towing vehicle of a loose connection or of theft of the trailer. U.S. Pat. No. 2,564,520 to Biasdell discloses mounting a lamp on the trailed vehicle which is energized when a proper connection is made. U.S. Pat. No. 3,710,370 to Quilici et al. teaches mounting both visual and audio indicators on an automobile's dash board, thus signaling the improper coupling to the driver while the vehicle is in motion. U.S. Pat. No. 4,593,264 to Engle discloses a circuit which actuates a single warning signal (the vehicle's horn) when the ball-socket coupling becomes loose and in the case of an attempted theft of the trailer. Thus, in Engle '264, the vehicle's horn will sound during normal connection and disconnection procedures, as well as when the vehicle is in motion, should the trailer coupling become loose. Sounding the vehicle's horn in the aforementioned circumstances is undesirable, irritating and potentially dangerous. U.S. Pat. No. 4,627,633 to Gehman et al. also discloses a hitch uncouple detecting and signaling apparatus, but does not, however, disclose a trailer theft alarm means. A later patent to Engle, U.S. Pat. No. 5,159,312, provides for a double switch system wherein a signal is provided upon detection of a loose connection of the ball to the socket, as well as upon detection of a loose connection between the ball and the towing vehicle frame structure. A warning is also sounded upon unauthorized removal of the hitch. The alarm signals are transmitted to a receiver, which may be in the cab of the vehicle, or in a remote location.
All of the aforementioned systems use a single alarm, usually the horn of the vehicle, to alert the vehicle's driver to a loose hitch connection or an unauthorized removal of the trailer. Thus, the horn may blast even when the vehicle is in motion, with unpredictable effect upon the driver and surrounding vehicles. Furthermore, none of the solutions proposed above teach any selectivity in the setting of the alarms. The vehicle's operator is therefore not able to selectively set only the loose connection alarm, or only the theft detecting alarm.